The Cost of Betrayal
by Book girl fan
Summary: Remus Lupin died in Azkaban, betrayer of the Potters and murderer of Peter Pettigrew. Sirius Black raises Harry Potter. One day, the story changes.


' _WEREWOLF REMUS LUPIN DIES IN PRISON_

 _Remus Lupin, the Dark wizard notorious for his betrayal of the Potters six years ago, died in his cell at Azkaban last night of self-inflicted injuries. The werewolf, a former friend of the Potters before his hideous betrayal..._ '

Sirius tore his gaze away from the paper, not allowing himself to be dragged back into those painful memories. Remus deserved to be dead. He'd killed James and Lily, killed Peter, tried to kill Harry – he deserved to die for that. It was only because the Ministry had not been quite sure if werewolves even had souls that he had been spared the Kiss years before.

Still, Sirius couldn't help but feel a pang at the thought that he was now the last of the Marauders. The Marauders had been broken every since Remus betrayed them all, but even a broken bond was still a bond. This final tie, a last link to childhood and the boys they had been, had finally died.

FOUR YEARS LATER

"Sirius?"

Sirius turned around to look at his godson, his smile turning into a frown at Harry's expression. "What's wrong, Harry?"

"Fred and George showed me your old map at Christmas – I don't think they know it's yours, though – and I saw..." he hesitated. "I saw Peter. Peter Pettigrew."

Sirius couldn't breathe.

"Isn't he dead, Sirius? Lupin killed him, after betraying my parents."

"Yes." Sirius finally found his voice. "That's what happened." It had to be what had happened. As painful as it had been for all these years, living with the guilt that he had refused to be the Secret Keeper, hadn't managed to convince James and Lily that Remus couldn't be trusted, Peter should be Secret Keeper instead... As painful as that had been, it was infinitely better than the alternative; that they _had_ chosen Peter, and Peter had betrayed them and framed Remus. That Remus, _Moony_ , had died in Azkaban an innocent man, while Sirius had told Harry stories of his Uncle Peter, who was brave and kind and good, and had died trying to bring his parents' killer to justice. "The map must be wrong."

Harry frowned. "But you told me the map is never wrong."

"Even the Marauders Map can be wrong once." Just like the Marauders, who trusted the wrong person and died for it.

Harry shook his head wildly. "But it wasn't just once! Every time I looked, Peter's name was always there. I even tried to find him once, but all I found was Scabbers."

"Scabbers?" Sirius asked half heartedly.

"I told you about him." Sirius knew more than saw that Harry had just rolled his eyes. "Ron's rat."

For the second time in the last few minutes, Sirius couldn't breathe.

"Harry," he asked, trying futilely to keep his voice from shaking, "could you describe Scabbers for me?"

"He's just a rat. Ron got him from Percy, because Percy is a prefect now so he got an owl, and Ron got Scabbers. Ron told me about it."

"Describe him, Harry!" Part of him knew he was probably frightening his godson, but right now, that didn't matter as much as finding a way to disprove his horrible suspicions.

"He's just a rat!" Harry repeated, eyes wide. "He's really old, and he sleeps a lot, and one of his toes is missing, but Ron didn't do it! He was always like that."

Sirius breathed deep, for what felt like the first time in a long while. "No, he wasn't."

He reached out and grabbed Harry's arm, pulling the boy along behind him. "Come on, we need to go. We need to go to the Weasleys, and the Ministry will have to know, and Dumbledore–"

"No!" Harry tore his arm out of Sirius' grip, looking up at his godfather with furious eyes. "Tell me what's happening! Why are we going to the Weasleys? Why does it matter that Scabbers is missing a toe? And what's it all got to do with Uncle Peter?"

Sirius growled involuntarily. "He's _not_ your Uncle Peter."

Harry took half a step backwards.

Sirius started to move forward, but stopped, unsure what he even intended to do. He ran a hand over his face. "Do you remember those stories I used to tell you?" he started. "About the dog and the wolf and the rat and the stag? How they had lots of adventures together?"

Harry nodded, looking slightly more comfortable, if confused on the relevance. "And you named them after you and Dad and Unc–" he stumbled over the words before replacing it with, "the Marauders."

Sirius nodded, then shook his head. "Not quite. Harry, I didn't name them after the Marauders. They are the Marauders."

Harry frowned. "How can they be the Marauders? They're animals."

"Like this." Sirius transformed into Padfoot, galloping up to Harry and giving his face a thorough licking.

Harry laughed, then stared at him with awe. "Padfoot?"

Sirius transformed back. He smiled sheepishly. "Yeah. I'm Padfoot."

"Which one was dad? Was he Moony? No–" Harry's eyes grew wide. "Lupin's a werewolf! _He's_ Moony! You and Dad were friends with a werewolf?!"

Sirius' lips twisted into a habitual scowl at Remus' name, before he forced them to smooth out. "Yes. I was Padfoot, Re– Lupin was Moony, Peter was Wormtail, and your dad, he was Prongs."

Harry hopped up and down, apparently torn between excitement and indignation. "But why didn't you tell me? You said they were just stories!"

Sirius winced. Now didn't seem to be the time to explain how technically, what they'd done was illegal, or how much it had hurt to change into Padfoot knowing that they'd done it to help Remus and now Remus was the reason James and Peter were dead, especially as it seemed that might no longer be true. "We can talk about that later. For now, remember that I said Peter was Wormtail? The rat?"

"Uh huh."

Sirius hesitated, unsure how to put it, before blurting out, "I think Scabbers might really be Peter."

"Really?!" Then Harry frowned. "But you said Uncle Peter was dead. That Lupin killed him."

"I thought he had. Everyone thought he had. But, the map," he gestured vaguely, hoping Harry would understand.

Harry nodded sagely. "The map is never wrong."

Sirius breathed a sigh of relief, grinning. "Exactly."

"So then what happened to Uncle Pe – Peter?"

Sirius drew Harry over to the couch, sitting down beside him. "Do you remember what I told you about how your parents died?" he asked, looking directly into Harry's eyes. Even all these years later, they still looked so much like Lily's, but were now more serious than Lily had ever had to deal with at that age.

"Lupin betrayed them, and told Voldemort where they were, and he came and killed them," Harry recited softly. "Then Unc– Peter found Lupin, and Lupin killed him too, and a whole street of Muggles. When they found him, he kept saying he was sorry, but if he was really sorry my parents wouldn't be dead." A tinge of bitterness crept into Harry's voice at this, and Sirius drew him closer, the two of them taking a silent moment to breathe and mourn. Over the years, the pain had faded, but it was times like these that made it so evident the damage that had been done that Halloween night.

"There's something I haven't told you, though," Sirius said, drawing back from the hug, but still keeping one arm around Harry. "James and Lily... Your parents, they asked me to be Secret Keeper first. I said no, I was too obvious, and told them they should pick Peter, that no one would ever suspect him." He tried to keep his voice neutral. Whatever he suspected, Harry needed to hear the whole story first. "Lily insisted on it being Remus. They were always very close, and neither of your parents believed that he was the traitor, no matter what I said to them. Then, when I was on a mission, there was another attack, and they had to go into hiding, quickly. By the time I was back, it was done. They refused to tell me, for my own safety. If I was going to be the decoy, it was better I had no knowledge to give away." He left unspoken his suspicion at the time that Lily had not wanted him to know out of a fear he would lead the Death Eaters to Remus. It had been a thought born purely out of paranoia, and was unworthy of the brave and caring woman Lily had been.

"I always thought they had gone ahead and made Remus the Secret Keeper. Most of our friends thought it was me, but after Peter, after everything, they believed me that I hadn't betrayed them, that Peter was right and Remus was Secret Keeper, and that was why Remus had killed him."

"But Lupin didn't kill him. He's alive." Harry's glasses glinted as he tilted his head thoughtfully. "If Remus didn't kill him, then why did he pretend he did? Why did he stay as Ron's pet?"

"That's what I'm going to find out." Sirius jumped to his feet again. "We're going to the Weasleys, and we need someone from the Ministry to watch us, to verify whatever happens."

"Ron's dad works at the Ministry," Harry suggested. "Couldn't he do it?"

"Well..." Part of him was reluctant to trust something so important to Mr Weasley when for so many years he hadn't even noticed his son had an Animagus for a pet, but the more sensible part of him, the part that had only really started to develop ten years ago when Harry was placed in his keeping, told him that no one had even known they were Animagi, and it wasn't like he had done any better. Besides, this was the fastest way to get the answers he needed. "Sure. Mr Weasley should be enough. Now let's go!"

He rushed back over to the fireplace, and this time, Harry willingly came with him. He let Harry go through first, reasoning that if Peter was there, he would find it less suspicious, as Harry often came over during the holidays. Before stepping through the fireplace, he looked around at the house that he and Harry had shared for ten long years. For a moment, it flickered, another reality coming in to view - a reality where he was taking Harry back to James and Lily's after a stay with his godfather, Moony just upstairs after a difficult full moon and Wormtail keeping him company - a world where James and Lily had never been betrayed, but they had had the happily ever after they deserved. Then he blinked, and the vision was gone. James and Lily were dead, and Remus was too. Peter had either betrayed them or died as well. Either way, their happiness had been shattered, with only him and Harry left to carry on and find out the truth.

He turned away, and stepped through the fireplace.


End file.
